1. Field of the Invention
The present invention relates generally to emergency eyewash stations, and more particularly to an impeller assembly for such stations.
2. Background of the Related Art
Emergency eyewash stations take many forms, including plumbed stations, self-contained fixed-mounted units and portable units. Generally speaking, these stations are designed to dispense eyewash fluid (typically water) upon demand.
The plumbed eyewash stations are generally connected to the water supply pipes of an existing sink or are installed as a stand-alone emergency eyewash station with the water supply and draining connected to the regular building water systems. An example of a plumbed eyewash station is found in U.S. Pat. No. 5,740,569 issued to Gurries, II et al, which discloses a rotatable spray nozzle mounted to the base of a regular laboratory sink. The spray nozzle is piped directly into the main water supply and includes a valve that is opened when the spray nozzle is rotated into active position above the sink. Although plumbed eyewash stations generally provide instant availability of a washing spray they suffer from the disadvantage of relying on ordinary tap water as the cleansing agent. For example, tap water may carry bacteria and other unknown chemicals and contaminants that could cause infection of the eyes. It has been recognized that it would be more advantageous to have a system that used an eyewash fluid that was known to be free of foreign substances, i.e. filtered, purified or sterilized.
Attempts have been made to retrofit plumbed stations with an external source of eyewash fluid that has been purified or sanitized. U.S. Pat. No. 6,070,279 issued to Lundstedt discloses one such retro-fit system. However, the Lundstedt patent relies upon the force of gravity to dispense the eyewash fluid from the station. Although the force of gravity offers several other advantages, it lacks the advantage of being able to maintain a constant and steady flow of eyewash fluid from the dispensing head of the station. In fact, the pressure steadily dwindles as the reservoir empties.
Turning to standalone wall-mounted and portable units, these stations typically have internal reservoirs that also rely upon the force of gravity to dispense the eyewash fluid. The U.S. Pat. No. 4,881,283 issued to Liautaud shows an example of a wall-mount unit.
In an effort to encourage more suitable eye wash facilities, the American National Standards Institute (ANSI) promulgated voluntary standards for portable eye wash fountains relating to flushing periods and the rate of flow of wash fluid. These standards dictate that portable eye wash fountains should deliver no less than 0.4 gallons per minute (1.5 liters per minute) of eye wash fluid for a time period of at least 15 minutes. Responsive to the new ANSI standards, several new designs emerged seeking to provide the required flow rates for the minimum periods of time. For the most part, the eye wash stations currently on the market do provide the required flow rates for the minimum period of time.
However, newer ANSI and OSHA regulations have created additional issues that will need to be addressed, and will require improvements to the existing designs to maintain compliance. In particular, upcoming OSHA regulations will soon require the use of “sterile” eye wash fluids. As with any use of a sterile fluid, there is a desire to maintain sterility of both the source of the fluid and throughout the delivery paths and delivery mechanisms, including all delivery lines, nozzles, and pumps, if included in the delivery system.
Therefore, there is a need for new emergency eyewash systems to provide a sterile source of eyewash fluid, to maintain a steady and constant flow of eyewash fluid from the source, and to provide a sterile delivery path from the source to the delivery site.